EFFECT OF CHARGE ON STRUCTURE - STEPWISE PROTONATION OF [EFE(3)(CO)(9)](2-) (E=SE, TE) AND ISOLATION OF THE NOVEL MIXED-METAL CLUSTER [TEFE3(CO)(9)(MU-CUCL)](2-)

The clusters [EFe(3)(CO)(9)](2-) (E = Se, Te) were protonated stepwise with triflic acid to produce both the monohydride clusters [HEFe(3)(C O)(9)](-) and the dihyride clusters H(2)EFe(3)(CO)(9). The effect of t he presence of the hydrides as well as that of the overall cluster cha rge on the structure was probed both spectroscopically and crystallogr aphically. The C-13 NMR shifts and the IR stretching frequencies of th e carbonyl ligands was found to be correlated with the cluster charge in a linear fashion, [PPN][HSeFe3(CO)(9)] crystallizes in the monoclin ic space group P2(1)/c (No. 14) with a = 9.359(2) Angstrom, b = 29.648 (6) Angstrom, c = 16.057(3) Angstrom, beta = 101.23(3)degrees and V = 4370.1(15) Angstrom(3). The isostructural telluride [PPN][HTeFe3(CO)(9 )] also crystallizes in the monclinic space group P2(1)/n (No. 14) wit h a = 8.925(2) Angstrom, b = 13.985(3) Angstrom, c = 35.798(7) Angstro m, beta = 97.13(3)degrees, and V = 4433.6(16) Angstrom(3). H2SeFe3(CO) (9) crystallizes in the monoclinic space group P2(1)/n with a = 8.862( 2) Angstrom, b = 11.503(2) Angstrom, 14.936(3) Angstrom, beta = 103.28 (3)degrees, and V = 1481.9(5) Angstrom(3). The tellurium analog H2TeFe 3(CO)(9) crystallizes in the centrosymmetric triclinic space group P ( $) over bar 1 (No. 2) with a = 7.8814(4) Angstrom, b = 8.9414(7) Angst rom c = 11.8243(4), a = 82.318(5)degrees, beta = 77.664(4)degrees, gam ma = 69.303(4)degrees, and V = 759.95(8) Angstrom(3). The reaction of [TeFe3(CO)(9)](2-) with either CuCL or Et(3)PCuCl produced the unusual cluster [TeFe3(CO)(9)(mu CuCl)](2-). A crystallographic study of the [PPN]+ salt confirmed the presence of the chloride ligand. [PPN]2[TeFe 3(CO)(9)(mu-CUCl)], which crystallizes in the orthorhombic space group Pbca (No. 61) with a = 24.274(5) Angstrom, b = 21.634(4) Angstrom, c = 30.363(6) Angstrom, and V = 15944.9(54) Angstrom(3), is therefore th e first example of a mixed iron-copper cluster which retains a halide ligand bound to copper.